Date Validation Regex: MM/DD/YYYY Format

Validate dates in US format (MM/DD/YYYY) with proper month and day range validation using regex.

Pattern Breakdown

^(0[1-9]|1[0-2])/(0[1-9]|[12]\d|3[01])/\d{4}$

Components

Detailed Breakdown

• (0[1-9]|1[0-2]) - Month alternation:
  • 0[1-9] - Months 01-09
  • 1[0-2] - Months 10-12
• (0[1-9]|[12]\d|3[01]) - Day alternation:
  • 0[1-9] - Days 01-09
  • [12]\d - Days 10-29
  • 3[01] - Days 30-31
• \d{4} - Year: exactly 4 digits

Examples

Valid:

• 03/15/2024
• 01/01/2024
• 12/31/2024
• 02/29/2024 (format valid, but may not be valid date)
• 01/01/0000 (format valid)

Invalid:

• 3/15/2024 (month not zero-padded)
• 03/5/2024 (day not zero-padded)
• 13/15/2024 (invalid month)
• 03/32/2024 (invalid day)
• 03-15-2024 (wrong separator)
• 15/03/2024 (wrong order - this is DD/MM/YYYY)

Implementation

JavaScript

const dateRegex = /^(0[1-9]|1[0-2])\/(0[1-9]|[12]\d|3[01])\/\d{4}$/;
dateRegex.test('03/15/2024'); // true
dateRegex.test('12/31/2024'); // true
dateRegex.test('13/15/2024'); // false (invalid month)
dateRegex.test('03/32/2024'); // false (invalid day)

Python

import re
date_regex = r'^(0[1-9]|1[0-2])/(0[1-9]|[12]\d|3[01])/\d{4}$'
bool(re.match(date_regex, '03/15/2024'))  # True
bool(re.match(date_regex, '12/31/2024'))  # True
bool(re.match(date_regex, '13/15/2024'))  # False (invalid month)

Go

dateRegex := regexp.MustCompile(`^(0[1-9]|1[0-2])/(0[1-9]|[12]\d|3[01])/\d{4}$`)
dateRegex.MatchString("03/15/2024") // true
dateRegex.MatchString("12/31/2024") // true
dateRegex.MatchString("13/15/2024") // false (invalid month)

Limitations

1. No leap year validation: Accepts 02/30/2024 (format valid, date invalid)
2. No month-specific day validation: Accepts 04/31/2024 (April has 30 days)
3. No year range validation: Accepts years like 0000 or 9999
4. Format only: Validates format, not actual date validity
5. Ambiguity with DD/MM/YYYY: Can be confused with European format

When to Use

• US date format validation
• Applications targeting US users
• When month comes before day
• Forms in US market
• Date input in MM/DD/YYYY format

For production, consider:

• Additional validation for actual date validity
• Using date parsing libraries to verify dates
• Validating year ranges
• Clearly labeling format to avoid confusion with DD/MM/YYYY
• Combining with date object validation